[QUOTE=fivemack;275365]You're measuring the size of the memory required to write down the candidate number N; what's relevant for CUDALucas is the amount of memory required to perform an FFT-based multiply of numbers the size of N, which is a good deal bigger (firstly because you can only fit about eighteen bits of N into each 64-bit floating-point number, and secondly because the CUDA FFT uses a lot of scratch space to allow it to use hundreds of threads).[/QUOTE]

Ah, okay. Makes much more sense, especially the threadedness. Thanks.

[QUOTE=Lorenzo;275350]All done works!

[CODE]Iteration 10000 M( 290000033 )C, 0x9e2181b8405a2511, n = 16777216, CUDALucas v1.2[/CODE]FFT size 16M![/QUOTE]

Err, actually not: the cufft size is initialiased as only half of n:

[CODE]cufftPlan1d(&plan, [B]n/2[/B], CUFFT_Z2Z, 1)[/CODE]

[QUOTE=aaronhaviland;275402]Err, actually not: the cufft size is initialiased as only half of n:

[CODE]cufftPlan1d(&plan, [B]n/2[/B], CUFFT_Z2Z, 1)[/CODE][/QUOTE]

:drama: Too bad.

Oops, i find in FAQ:
[CODE]Exponents: 2<=Exponent< 151,150,000
Exponent< 39,800,00  2MB FFT size
Exponent< 79,600,00  4MB FFT size
Exponent<159,200,00  8MB FFT size[/CODE]

No more question :redface:

[QUOTE=Lorenzo;275430]No more question :redface:[/QUOTE]
No, there are still basic questions (for me):
1. what is the max expo possible? how much GPU memory is needed for each FFT size?
2. what are the fft size borders beyond 4m?
i only tried up to 4m on my own.

I will try later but anybody must already have tested it...

Hi ,aaronhaviland
[QUOTE=aaronhaviland;275402]Err, actually not: the cufft size is initialiased as only half of n:

[CODE]cufftPlan1d(&plan, [B]n/2[/B], CUFFT_Z2Z, 1)[/CODE][/QUOTE]
GIMPS(Prime95,GIMPS Web,MLucas,GLucas,...) use real data size.

[QUOTE=msft;275673]Hi ,aaronhaviland

GIMPS(Prime95,GIMPS Web,MLucas,GLucas,...) use real data size.[/QUOTE]

Right, but I thought the question was about the limitations of CUFFT's transform sizes.

[QUOTE=aaronhaviland;275874]Right, but I thought the question was about the limitations of CUFFT's transform sizes.[/QUOTE]
NVIDIA not announce CUFFT's work area size and limitations ,we can only do the experiments.

Sorry people, want try CUDALucas too, I downloaded CUDALucas.1.2b.zip, extracted, installed CUDA Toolkit 3.0 from nvidia website, wanted to compile CUDALucas using make and got an error: CUDALucas.cu:87:26: fatal error: cutil_inline.h: Directory or file does not exist. What is wrong? Do I need some CUDA patch? Which one? I am lost... I am using Ubuntu64 on Core2 Duo and GTS250.

Check your Toolkit version. I'm pretty sure the current release is either 4.1 or 4.2. There's also some instructions you have to follow during installation regarding various *PATH variables.

Okay, I replaced Toolkit with version 4.0, downloaded also GPU Computing SDK. Now I moved a little farther, and stopped at the error:

gcc: setup.cu: Directory or file does not exist
gcc: warning: '-x c++' after last input file has no effect
gcc: no input files
make: *** [setup.o] Error 1

Unless CUDA threw an error about the gcc version being >4.5, I can't help. Sorry.